Can you switch between different material versions?
A bit dirty but you could use a node group:
Select the Mix Shader that you use as a shutter, press CtrlG to create a group. Once done, press Tab to go into the group and unplug the factor socket that will be created by default. If you play with the factor value it will switch from a shader to another:

Press Tab again to go out. In all your other materials create the group you've created with ShiftA and plug the shaders:

Now select one of these groups and play with the Mix Shader factor value, it will switch all the other material Mix Shaders as well.